1. Field of the Invention
This invention relates to digital video signal processing methods and apparatus. Embodiments of the invention are particularly, but not exclusively, intended for use in broadcasting studios.
2. Description of the Prior Art
A digital slow motion processor comprising a large random access memory capable of storing several seconds of a digital video signal and operating cyclically has been proposed by us for use in broadcasting studios. Thus, by placing the slow motion processor in parallel with a transmission or recording path, that is between a video camera and a transmitter or a recorder, the last few seconds of the transmitted or recorded signal is always available in the memory. In the case, for example, of a sports broadcast, the input to the memory can be cut at the end of a particular bit of action, and the slow motion processor can then read out the stored few seconds of the digital video signal including the bit of action for repeated transmission or recording. The read-out will usually be at a non-standard speed, most usually in slow motion, and the slow motion processor includes adaptive interpolation filters of known form to do the necessary field rate conversion to provide an appropriate sequence of fields at the system field frequency for transmission or recording.
The present invention is concerned with an adaptation of the form and use of apparatus similar to such a slow motion processor to permit cut editing; that is, to permit omission from transmission or recording of small unwanted portions of a digital video signal being received from a live source such as a video camera.